cat runs much hotter with A/C on
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Cadillac Catera and Cimarron Forum Discussion, cat runs much hotter with A/C on in Past Cadillac Vehicle Discussion; I have had some cooling problems with my '97 and thought i had them all licked...Not so fast, my friend! ...
  1. #1
    szaeske is offline Cadillac Owners Member
    Automobile(s): 1997 Cadillac Catera
    Join Date
    May 2008
    Location
    St. Louis, MO
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    cat runs much hotter with A/C on

    I have had some cooling problems with my '97 and thought i had them all licked...Not so fast, my friend!

    actually two questions, which i think may be related...

    1. Temp spikes after about 20 miles at highway speed. Doesn't really matter what the ambient temp is, but when i go to work in the morning or when i head home at night, the temp will either be about a needles' width below the center line on the gauge or maybe a needles' width above the center line. After about 20 miles however, the temp will spike to between 5/8 (the small tick mark after 1/2) and the 3/4 mark. If the A/C is off, the system recovers within a couple minutes to between the 1/2 and 5/8 marks, but never recovers to being at or below the 1/2 mark like it was before the spike.

    Just seems to be a pretty decent sized spike when i am at a pretty constant driving condition. I.E. highway speeds with cruise control engaged on fairly flat highway.

    2. This leads to the second part. If the A/C is on, there is a much bigger spike. It will spike to what i call dangerous territory (around the 3/4 mark). If the A/C is on and it spikes to about 3/4 it will cool down a bit, but only to about the 5/8 mark. If i turn the A/C off, i will notice an almost immediate recovery to between the 1/2 and 5/8 marks on the gauge (closer to the 1/2 mark).

    I wouldn't expect the A/C to cause that much of a load problem on a 3.0L V6 at 2400-2500 RPM. I also don't see any obvious cooling system problems. All three fans are working and the aux pumps are working. The thermostat seems like it is opening just fine.

    No coolant leaks (not anymore, anyway), coolant is clean and topped off. Not sure where to go with this, now.

    Thanks,

    scott

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  3. #2
    investor74 is offline Cadillac Owners Enthusiast
    Automobile(s): '97 Forest Green Catera
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    Re: cat runs much hotter with A/C on

    You can try a coolant flush and fill, but it seems like your Catera is operating normally. At least, it is operating like our '97 has since we bought it new. Stays at or below 1/2 all winter and into spring. In the mid 90's summer heat we have been having, warms up to 5/8 with occaisional up to 3/4 if stuck in traffic. BTW, I don't consider 3/4 "dangerous". The redline is actually at 7/8.

    Barry

  4. #3
    Army_MP_From_MO's Avatar
    Army_MP_From_MO is offline Cadillac Owners Fanatic
    Automobile(s): 1999 Cadillac
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    Re: cat runs much hotter with A/C on

    Sounds like you need a new thermostat

  5. #4
    callingmonroe's Avatar
    callingmonroe is offline Cadillac Owners Member
    Automobile(s): Cadillac Catera
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    Richmond, Virginia
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    Re: cat runs much hotter with A/C on

    Here is what I know... Mine is the same and this is with the Aux. Heat water pump disconnected due to a short. So I ordered a new one and will install. However, it is the exact same problem you are saying, and if I am correct that 1/3 of my system is not operating at all, then it could very well be a thermostat.

    If by chance your radio stops playing and your fan stops working when in drive, it would be the Aux pump, which leads to a 10 amp fuse. So keep an eye on this. if this happens disconnect the water pump mentioned above. I know this because my buddy has access to the wiring diagram from GM.

  6. #5
    lakesidepark is offline Cadillac Owners Fanatic
    Automobile(s): 1997 Catera
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    Apr 2006
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    Nashville TN
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    Re: cat runs much hotter with A/C on

    Have you pulled the fans off the front of the condensor? It is amazing how much garbage (insects, leaves, dirt) gets packed in there. It will dramatically decrease your cooling ability.

    Since the AC makes it run hotter, I suspect blockage, either in the air flow or the coolant flow. The AC forces the fans to full speed anytime it is on, and I noticed it actually makes my car run cooler at idle with it ON.

    Its much easier when you can remove the radiator and the condensor to get to the front fans (yes it means evac of the AC so the condensor can be removed). Thats how I did it since I was servicing the AC at the same time. There may be another way to get to the front fans besides removing all the hardware. If your car is above 120000 and its never been done...then you need to check it.

    Mine was packed so much with dirt it was surprising the car didn't totally overheat. There was even trash packed in the air tube going to the alternator. That had to help the electrical.

    Temp gauge doesn't get to the 5/8 mark anymore even at 100 degrees outside unless I turn the AC OFF (not likely when its that hot outside). It cycles just below and just above the center line.

  7. #6
    yermo13 is offline Cadillac Owners Member
    Automobile(s): cadillac catera 98
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    Exclamation Re: cat runs much hotter with A/C on

    well mine was acting i the same way so i decided to changed the thermostat and flushed the system but now my car is heating more than the normal tempeture above the half and i wonder what i did wrong? some avise is wellcome?

  8. #7
    yermo13 is offline Cadillac Owners Member
    Automobile(s): cadillac catera 98
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    Re: cat runs much hotter with A/C on

    also i forgot to mention that i use the 180f thermostat and dexcool

  9. #8
    Enz
    Enz is offline Cadillac Owners Member
    Automobile(s): Cadillac
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    Re: cat runs much hotter with A/C on

    I have a question for you - My engine temp needle recently stopped working. Would this be a sensor/fuse issue that I'd find under the steering column? or under the hood? Loose wire/connnection? *no A/C. Other than that - everything works as expected.
    Sontov

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